Dynamically Update Class Definitions?

[chrisspen at gmail.com]

Is there a way to loop through all instantiated objects and update
their classes when a source file changes? I know about Michael Hudson's
method
(http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/160164), but
you have to modify all your classes to subclass AutoReloader. Is there
something less intrusive (visitor pattern?) that you can use like
update(old_class, new_class) to automagically do the work?

Chris